Anti-collision systems in vehicles are known. Systems currently in use employ displays of the vehicle's own region that are derivatives of systems based on inertial, radar, and sonar sensors, and provide a visual representation of the existence of another vehicle. Such systems provide limited information on how to optimally steer away from any potential conflict.
An example of a system currently used in aircraft is the Traffic Alert and Collision Avoidance System (TCASII). When a second aircraft, known as the intruder, is detected in the first aircraft's onboard system, a warning signal is transmitted to the cockpit crew. This is known as a traffic advisory signal. The system then emits an audible and visual instruction for the pilot to either climb or descend. This is known as the resolution advisory signal.
A similar traffic advisory signal is received by the crew of the second aircraft if so equipped. However the resolution advisory instruction received at the second aircraft (if so equipped) is the opposite to that given to the first aircraft. The system therefore provides a suggestive manoeuvre (either climb or descend) to both aircraft to avoid a collision. Whilst there is a cockpit display for the system, it is quite cryptic and might not visually identify a second aircraft in the conflict region.
As discussed above, TCASII provides only a climb or descend option to the pilot to avoid the conflict. The pilot does not receive instruction to turn or change speed. Further, the TCASII system cannot adequately handle multiple aircraft in a potential collision zone.
Another prior art system for identifying conflicts is the air-to-air radar display. Such a display is usually used in fighter aircraft and is not implemented in civil vehicles. FIG. 1 shows the main features of the display that is primarily used to target enemy aircraft in air-to-air combat (Figure reference: Shaw, R. L., (1988) Fighter Combat The Art and Science of Air-to-Air Combat, Patrick Stephens Limited). When a target is out of range, the display simply directs the aircraft, or own-aircraft/ownship, on a collision course with the target. The pilot can achieve the required direction by steering the dot 100 so as to place it in the centre of the display.
The display of FIG. 1 is essentially a projection of the front rectangle of directions scanned by ownship's sensors, such as radar. Thus a direction in 3D becomes a point in 2D on the display. The line of sight (LOS) 102 of the target becomes a point, which in this instance is represented by a square to differentiate from other symbols displayed to the pilot. The allowed steering error (ASE) circle 104 indicates a range of possible launching directions. That is, when the steering dot 100 lies inside the circle 104, a launch can be successful. The display may contain other information like time and distance to the intercept point (not shown). It will be appreciated that such a display can also act as a collision avoidance system, where the pilot simply steers ownship away from the target.
A further prior art system is disclosed in U.S. Pat. No. 6,970,104 to Knecht and Smith. Here, flight information is used to calculate a conflict region within a reachable region of ownship. The display gives an artificial three dimensional representation (heading, speed and altitude) of a conflict region to the pilot. The display does not show three dimensional positions relative to ownship, and only displays manoeuvre space in relation to the conflict region. That is, the pilot must identify a region away from the conflict region, calculate the required heading, speed and altitude from the display, then manoeuvre ownship in accordance with these calculations.
The conflict region of Knecht and Smith is calculated from assumptions about how both aircraft could turn, climb, descend, accelerate or slow down. Thus their conflict region requires both questionable assumptions and considerable processing of data, rather than incontrovertible information and the display of directly meaningful data.
Further, the pilot is not informed of the level of danger associated with the chosen heading, speed and altitude. The pilot might be placing own-aircraft into a future conflict situation if the conflict region is just beyond the chosen time horizon (look ahead minutes) and is therefore not displayed.
Therefore, there is a need to provide a display for a vehicle to immediately inform the pilot of the vehicle of a potential conflict situation, and provide an indication as to the inherent level of danger for potential manoeuvres of the vehicle.